Let me see if I’ve got this right.
If the government are obliged (as seems to be likely, although we should not pre-judge the outcome of today’s Supreme Court hearing) to present a Bill to parliament to trigger Article 50, then Labour will seek to amend that Bill to constrain the form of Brexit. Without their amendment, they claim that Brexit will lead to a drop in wages, public spending and living standards. But if their amendment fails, they will not oppose either Brexit or the Bill itself, even if it does lead to a drop in wages, public spending and living standards. This is called defending ordinary working people from the Tories.
The reason that they can’t oppose either Brexit or the Bill is that the majority of the electorate voted to leave. But, actually, 48% voted to stay; with Labour now supporting the process of triggering Article 50, the voices of those 48% are represented only by the smaller (in UK terms) parties, who between them account for only around 10-12% of the seats in parliament. Labour, as the main opposition party does not see it as its job to speak for the main body of opposition amongst the electorate, even if most of its MPs agree with that 48%.
The reason for that seems to be that the majority of the electorate in Labour constituencies voted to leave, even though all the evidence shows that the majority of those who actually voted for the Labour MPs themselves voted to remain; the majority for leave came from those who voted for their opponents.
So, to sum up: Labour MPs feel that it is their duty to speak up for those who voted against them and against the majority of those who voted for them, even if they believe that the outcome of that will be a drop in wages, public spending and living standards which will disproportionately impact on those who actually did vote for them.Strange business, this politics.